package Test;

import java.util.Random;

public class Test1 {
    public static void main(String[] args) {
        String code = Gen(4);
        System.out.println("验证码: "+code);
    }

    public static String Gen (int len){
        String code = "";
        char[] chs = {'a','b','c','d','e','f','g','h','i','j','k',
                'l','m','n','o','p','q','r','s','t','u','v',
                'w','x','y','z','A','B','C','D','E','F','G',
                'H','I','J','K','L','M','N','O','P','Q','R',
                'S','T','U','V','W','X','Y','Z','0','1','2',
                '3','4','5','6','7','8','9'};
        Random rand = new Random();
        for (int i = 1; i <= len; i++) {
            int index = rand.nextInt(chs.length);
            code += chs[index];
        }
        return code;
    }
}